flakes: Migrate the config and miku to flakes

modules/programs/tmux/default.nix

@@ -1,9 +1,15 @@
-{ config, pkgs, ... }:
+{ config, lib, pkgs, ... }:
 
-{
-  config = {
+let
+  cfg = config.ptw.programs.tmux;
+in {
+  options.ptw.programs.tmux = {
+    enable = lib.mkEnableOption "Enable and configure tmux using HomeManager";
+  };
+
+  config = lib.mkIf cfg.enable {
     environment.systemPackages = [ pkgs.tmux ];
-    home-manager.users."${config.system.singleUser}".programs.tmux = {
+    home-manager.users."${config.ptw.system.singleUser}".programs.tmux = {
       enable = true;
       extraConfig = ''
         set -g mouse on